The present invention relates to a probe scanning apparatus for a probe microscope, and more particularly to a probe scanning apparatus for a probe microscope designed to enable a higher resonance frequency of a probe scanning mechanism.
There is an apparatus using a piezo-scanner as one example of a probe scanning apparatus for a scanning type of probe microscope based on the conventional technology. In this piezo-scanner, the relation (impressed voltage-displacement characteristics) between an impressed voltage to an electrode of a piezo element and a displacement rate thereof is non-lineaty, so that the displacement rate can not be made larger. It is also difficult to handle the piezo-element because it is required to impress a high voltage in a range from around hundreds of volts to a thousand volts to the electrode, which requires shielding of the periphery thereof or a protection circuit that reduces the voltage when a cover of the apparatus is opened.
Therefore, the owner of the present invention developed a sample positioning apparatus in which a pulse motor as a coarse adjustment mechanism in the Z-axial direction and screws or the like were replaced with a housing with a viscous body accommodated therein, a heater mechanism, and a poise coil mechanism, and in which a piezo-element as a fine adjusting element in the z-axial direction was also replaced with a spring element, and a patent application for the developed apparatus was filed in Japan under Japanese Patent Application No. HEI 8-25201 and in the United States under Ser. No. 08/800,074.
With this sample positioning apparatus, all the problems relating to the conventional type of piezo-scanner can be eliminated, but there is provided only the apparatus with the coarse adjustment mechanism in the Z-axial direction and the fine adjustment mechanism in the Z-axial direction integrated thereinto, and no consideration is found on the necessity that the scanning mechanisms in the x-axial and y-axial directions should be integrated into those mechanisms. The sample positioning apparatus based on the conventional technology has been used only, and no consideration has been made on the possibility of using it in scanning with a probe.
Then, the owner of the present invention developed the probe scanning apparatus as shown in FIG. 9, for which a patent application was filed in Japan under Japanese Patent Application No. HEI 8-118015 and in the United States under Ser. No. 08/855,543. This probe scanning apparatus has, as clearly understood from the figure, a first poise coil motor comprising a magnet 2 having a shaft section 3, a movable element 4 with a coil 6 wound therearound, and a membrane 5, each mounted in the upper section inside a frame 1. Fixed to the movable part 4 is a spindle 8 extending in the z-axial direction. Placed at the lower edge section of this spindle 8 is a displacement detector 9, and further a cantilever and a probe (chip) 10 are attached to the displacement detector 9.
On the other hand, the frame 1 has a slender pipe section 14 projecting to a sample chamber and a thick pipe section 15 communicated to the section, and an internal tube 13 is supported by a viscous body 17 inside the thick pipe section 15. Also the spindle 8 is elastically supported by first and second springs 11, 12 held by the internal tube. A heating coil 16 is energized to soften the viscosity body 17 at the time of coarse adjustment in z-axial direction of the probe 10.
Attached to an inside section in the side of the frame 1 is a second poise coil motor comprising a magnet 21 having a shaft section 22, a movable element 23 with a coil 25 wound therearound, and a membrane 24. Fixed to the movable element 23 is a spindle 27 extending in the x-axial direction, and a free edge of the spindle 27 is fixed to a portion 15a of the thick pipe section 15 through a fine line 26. Also a third poise coil motor is attached, although it is not shown in the figure, to an inside section in the side of the frame 1 in a different direction by 90.degree. from the second poise coil motor, and the movable element of third poise coil motor and the thick pipe section 15 are connected to each other through a fine line and a spindle neither of which are also not shown in the figure. Then, by driving the second and third poise coil motors, scanning in the x-axial and y-axial directions is executed by the probe 10.
Provided in a position opposite to the probe 10 is a sample base 31 and a sample 32 to be tested is placed thereon. The sample base 31 is placed on a stage 33 for coarse adjustment in x-, y-, z-axial directions.
By the way, in the probe scanning apparatus having the configuration as described above, it is impossible to make higher a resonance frequency f0 of the fine adjustment mechanism in the z-axial direction comprising the first poise coil motor, spindle 8, displacement detector 9, and the probe 10. It is generally known that, in a probe scanning apparatus for a probe microscope, a scanning frequency in the Z-axial direction can be used for observation of a sample only at a range of 1/5 or 1/10 or less of the resonance frequency f0 of the fine adjustment mechanism in the z-axial direction. Accordingly, in the probe scanning apparatus shown in FIG. 9, it is impossible to observe a sample by means of fast scan with the probe because a resonance frequency f0 of the fine adjustment mechanism in the z-axial direction cannot be made higher.
An object of the present invention is to provide a probe scanning apparatus for a probe microscope which can resolve the problems in the conventional technology described above and also make higher a resonance frequency f0 of the probe scanning apparatus. Another object of the present invention is to provide a probe scanning apparatus for a probe microscope in which fast scanning with a probe can be executed at a high speed.